Two laboratories A and B carry out independent estimates of fat content in ice cream made by a firm. A sample taken from each batch gives the following fat content:

Batch No - 1 2 3 4 5 6 7 8 9 10
Lab A _ 7 8 7 3 8 6 9 4 7 8
Lab B _ 9 8 8 4 7 7 9 6 6 6

Is there a significant difference between the mean fat-content obtained by the two laboratories A and B?

The mean of any sample is

mean=\frac{sum.of.samples}{number.of.samples}

Find the mean for both samples and take the difference.

Hm, by the way Nhatkiem, the code for 'space' is '\,' [backslash comma]

Or just backslash and a space.

Oh, yes, you're right :o Less to type

Yes, and I'm bound to take the easy way out. LOL.

Oh really.. lol I was getting annoyed at the spaces not entering.. so.. periods haha

Two laboratories A and B carry out independent estimates of fat content in ice cream made by a firm. A sample taken from each batch gives the following fat content:

Batch No - 1 2 3 4 5 6 7 8 9 10
Lab A _ 7 8 7 3 8 6 9 4 7 8
Lab B _ 9 8 8 4 7 7 9 6 6 6

Is there a significant difference between the mean fat-content obtained by the two laboratories A and B?

You need to calculate the mean for sample A and also the standard deviation for sample A.
Then, also the mean for sample B and the standard deviation for sample B. Look up the formulae in your textbook. The mean for sample A should differ from that of sample B. But the question is 'IS that difference SIGNIFICANT?' or can it just be attributed to 'normal' variability in the data.

Then look up hypothesis testing: difference between two means in your textbook or elsewhere and follow the procedure for hypothesis testing.

You'll have to decide on the level of significance of the test if none is given. Typically, use a 5% level of significance.